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// Portions Copyright [2018-2019] [Payara Foundation and/or its affiliates]
package com.sun.enterprise.security.auth.realm;

import java.security.Principal;

import java.util.Enumeration;

/**
 * All users are principals ... perhaps in the native OS, perhaps not.
 *
 * <P>
 * Users always have authentication information, which is used to validate a user's preferred credentials. Different
 * kinds of realms use different kinds of authentication information. For example, realms could use X.509 public key
 * certificates, shared passphrases, encrypted passwords, smart cards, or biometric data to figure out if the user's
 * credentials are valid.
 *
 * <P>
 * Users typically have attributes that identify privileges granted/possessed by the user.
 *
 * @author Harish Prabandham
 */
public interface User extends Principal {

    /**
     * Returns the realm with which this user is associated.
     */
    Realm getRealm() throws NoSuchRealmException;

    /**
     * Returns the single requested attribute for the user.
     *
     * @param name string identifying the attribute.
     * @return value of that attribute, or null if no value has been defined
     */
    Object getAttribute(String name);

    /**
     * Returns an enumeration of the keys for the attributes supported for this user.
     */
    Enumeration<String> getAttributeNames();
}
